Re: [Boost-users] [GIL] Performance warning...

I am not an expert but I think on primitive types, there is no need to put a reference (and it may slows down the process). But the line I mentioned before concern a channel object, and I think this object stores many datas (maybe a byte array ?). 2009/11/28 Christian Henning

Lubomir, looking at the default_channel_converter the channels already arrive as a const reference. All I did was to make sure they are still const references in the channel_converter functions. In all cases the source channels should at least be const. Which allows for more compiler optimizations.

I did run the performance test in gil_test suite and the changes were marginal. Some tests were faster some were slower after the change.

Christian

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This was done on purpose. I don't know if it still holds, but it used to be that a const reference to a simple type like an int or char is slower

On Fri, Nov 27, 2009 at 6:13 PM, Lubomir Bourdev wrote: than

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passing the type by value. This is the same reason most STL algorithms take iterators by value. If you want to make this change it is important to verify that performance of simple built-in channel types is not adversely affected.

Lubomir

On 11/27/09 12:17 PM, "Christian Henning" wrote:

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Hi Eloi, you're correct and I'll fix that. I can even make it const reference. Running the test shows no real difference but that might be only because no expensive channels are being used.

I'll commit the changes asap.

Lubomir, please review the changes if your time allows. Affected files are channel_algorithm.hpp and gil_concept.hpp.

Thanks, Christian

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